1. Field of the Invention
The invention relates to a tailstock for machine tools, and more particularly to the tailstock for lathes that provide a clamping unit to increase the clamping force of a tail hydraulic tank of the lathe.
2. Description of the Prior Art
The conventional lathe is a machine tool that is specified in machining longitudinal work pieces with a round cross section. While in applying lathe to machine a work piece, one end of the work piece is fixed to a rotational spindle, while another end thereof is connected with a tailstock. Generally, the tailstock has a main body mounted fixedly to a station frame of the lathe. The main body may be equipped with a protruding lathe center for point-contacting the work piece so as to align the central line of the work piece and the rotational axis of the lathe. In performing the engagement between the work piece and the tailstock, the tailstock is moved manually or by a hydraulic force to protrude the lathe center toward the free end of the work piece till a tight contact is confirmed between the lathe center and the work piece.
However, as the dimension of the work piece to be machined by the lathe increases, the weight of the work piece as well as the load in the lathe becomes heavier. Thus, it is necessary to introduce a heavy-duty tailstock so as to meet the loading need. In the art, the one-piece piston design for each lateral side of the tailstock is believed no longer to meet the requirement of an upgraded clamping force. However, in the circumstance of the limited space available around the lathe tailstock, it is almost impossible to upgrade the tailstock for meeting the need of increasing clamping force for holding the work piece. Namely, it is an urgent need in an improved lathe tailstock for resolving the loading problem while in meeting a heavy-duty situation.